1. Field of the Invention
The present invention relates to a foldable electronic device, and more particularly to a foldable electronic device using a four shaft linkage mechanism.
2. Description of Related Art
Handheld electronic devices, such as mobile phones and personal digital assistants (PDA), have become one of the most indispensable equipments in our daily life due to their convenience and portability. In order to protect the keypad or screen of a mobile phone, a lifting cover design or even a sliding cover design is provided to replace the conventional leather casing used for covering the mobile phone. A user will not dial out or damage the keypad accidentally by the foregoing lifting cover or sliding cover.
FIG. 1A and FIG. 1B are diagrams of a mobile phone with the conventional sliding cover design, wherein the mobile phone is respectively open and closed. Referring to FIG. 1A and FIG. 1B, a single screen 110 is used when the mobile phone 100 is either open or closed. Using the single screen 110 helps to reduce the fabrication cost of the mobile phone 100. However, the keypad area 120 of the mobile phone 100 is small because that the space is occupied by the sliding mechanism when the screen moves relatively to the keypad. Accordingly, each key 122 has a small size, and it is very inconvenient for a user to operate the mobile phone 100 by the keys 122.
FIG. 2A and FIG. 2B are diagrams of a conventional mobile phone with the lifting cover design, wherein the mobile phone is respectively open and closed. Referring to FIG. 2A and FIG. 2B, the mobile phone 200 has a larger keypad area 220. However, two screens 212 and 214 are disposed inside and outside of the mobile phone 200 for convenient operation, so that a user can know whether there is any missed call or newly received message when the mobile phone 200 is closed. Such a double-screen design increases the thickness and the manufacturing cost of the mobile phone 200.